When using the JavaScript function Date.now in IE8 you may receive the following error:

‘Object doesn’t support this property or method’

This is caused by the fact that Date.now()wasn’t added to the JavaScript specification until ECMAScript 5. If you look at the functions entry on MSDN you will find the following under the requirements section:

‘Not supported in installed versions earlier than Internet Explorer 9. However, it is supported in the following document modes: Quirks, Internet Explorer 6 standards, Internet Explorer 7 standards, Internet Explorer 8 standards, Internet Explorer 9 standards, Internet Explorer 10 standards. Also supported in Windows Store apps.’

What this little gem means that even if you switch the document mode in IE9 onwards you wont hit this issue! The only way to test for this issue is to actually have IE8 installed.

Fortunately, there is a simple solution to this issue which I found on Ari Fuchs Tumblr. To fix the issue just add the following to the top of any javascript file that used the Date.now function:

Date.now = Date.now || function() { return +new Date; };

When trying to install Jenkins 1.491 on a Windows server I was faced with a failure message. Being used to problems with Java and 64-bit Windows my first though was that it was a Java related issue. It actually turned out to be something far simpler!

As part of the install Jenkins looks for the Windows Firewall and attempts to add an exception. On my server, Windows Firewall was disabled, as a different product was in use. This prevented an exception being added to the Windows Firewall rules for Jenkins which caused the install failure and subsequent rollback. The simple solution is to temporarily turn on Windows Firewall, install Jenkins and then turn it off again.

Of course, it would be better if later versions of the Windows Installer package for Jenkins didn’t fail if Windows Firewall is not enabled!222